The invention relates to an electrical switch, for the speed setting of an electric motor in an electrical appliance, including a movable actuating member and blocking means. The movable actuating member being movable from an initial position into actuating positions, in particular into a first and a second actuating position, in each case a function of the switch can be initiated. The blocking means is assigned to the switch, which blocking means can be switched over between a blocking state for blocking the movement of the actuating member and a release state for releasing the movement of the actuating member.
Such electrical switches are used in particular in electrical appliances, such as in portable electric tools or the like. For example, the portable electric tool may be an electric drill. The switch serves to switch an electric motor of the portable electric tool on and off and if need bealso to set the speed of said electric motor. In order to avoid unintentional switching-on of the portable electric tool, the electrical switch may be provided with a switch release.
Electrical switches having a switch release have been disclosed, for example, by DE-A 24 10 871. This switch has a housing, an actuating member arranged so as to be movable on the housing, and a plunger transmitting the movement of the actuating member into the housing and intended for acting on the switch. The actuating member can be moved from an initial position into actuating positions, in which in each case a function of the switch can be initiated. Assigned to the switch is a blocking means, which can be switched over between a blocking state for blocking the movement of the actuating member and a release state for releasing the movement of the actuating member.
The blocking means in this switch acts as a switch release. Once the actuating means has been switched over in the initial position from the blocking state into the release state, the actuating member can be moved into the actuating position. In the actuating position, however, no further action of a blocking means is provided, so that the blocking means on this switch only has single functionality.
The object of the invention is to provide a switch of the type mentioned at the beginning with blocking means of extended functionality.
In the switch according to the invention, first blocking means act on the actuating member in its initial position, and second blocking means act on the actuating member in a first actuating position of the latter. An actuating element having three switching positions for switching over the two blocking means is assigned to the switch. The first blocking means is in the blocking state in the first switching position of the actuating element. The first blocking means is in the release state and the second blocking means is in the blocking state in the second switching position. Finally, both blocking means are in the release state in the third switching position. Further refinements of the invention are described below.
The first blocking means is preferably arranged in the vicinity of the actuating member and the second blocking means is preferably arranged in the vicinity of the plunger. In this case, a gate on the top side of the actuating member may serve to guide a part of the first blocking means. A part of the second blocking means may be arranged centrally at the plunger.
The first blocking means may be designed like a switch release for the actuating member, and the second blocking means may be designed like a connection release for the actuating member. The actuating element can expediently be switched over only in the initial position of the actuating member.
In a special refinement, the first blocking means consists of an extension, in operative connection with the actuating element, and a corresponding stop arranged on the actuating member. In this case, the extension comes to bear against the stop in the initial position in the blocking state and can be moved laterally past the stop in the release state. The second blocking means is designed as a stroke limit for the actuating member in such a way that the motion path of the actuating member in the blocking state is limited to the first actuating position and in the release state is cleared for further movement into the second actuating position.
The stroke limit may in turn consist of a movable lug ring concentrically surrounding the plunger and of a corresponding stop provided on the actuating member. In this case, the stop comes to bear against a lug of the lug ring in the first actuating position in the blocking state and can be moved laterally past the lug in the release state. A pin which is on the actuating element and engages in a fork attached to the lug ring may serve to move the lug ring between the blocking state and the release state.
In order to ensure ease of operation by the user, the actuating element may be designed as a slide, pivoted lever, adjusting wheel or the like having three catch positions. An extension on the actuating element interacts with a catch spring for securing the catch positions. The first switching position for the actuating element is preferably formed by the center catch position and the second and third switching positions are preferably formed by in each case a lateral catch position. Function symbols may be provided on the actuating element, in which case the function symbol can be seen by the user in the respective switching position, said function symbol characterizing this switching position.
Furthermore, it is simple to fit the switch in the electrical appliance if the actuating element forms a preassembled module with the switch. For this purpose, a support part, for example, may be connected to the housing of the switch, the actuating element being mounted so as to be movable in the support part.
The advantages achieved with the invention consist in particular in the fact that certain functions of the switch can be selected and further functions can be blocked in the initial position of the actuating member. This effectively prevents functions which are not desired from being switched on inadvertently by the user, whereby the risk of accident for the user is also reduced. For example, the portable electric tool can be operated with a variable and if need be controlled speed, which is less than the maximum speed, in a first actuating position of the actuating member, whereas it can be operated with the maximum speed in a second actuating position of the portable electric tool, where the maximum speed is not controlled by the electronics. The user can block the second actuating position in a preselectable manner according to of the material to be worked, which results in an optimum working result.
In addition, said functionality is combined with a switch release already used hitherto.
Only a single actuating element is advantageously used for both blocking means, so that operation is simplified on the one hand and costs are also saved on the other hand.
The switch according to the invention achieves a further safety advantage for the user of the portable electric tool. Due to the design of the blocking means, the occurrence of a tilting moment at the actuating member is avoided even if the actuating member is subjected to excessive stress when the blocking means is in the blocking state. This effectively prevents the portable electric tool from being switched on inadvertently or inappropriately.